Trying to get the air compressor hooked up...

[Socophreak]

After reading your problem, are you sure motor is getting voltage? Is the pressure switch reading voltage? Have you checked the capacitors? Microfarad ratings/readings? I see that you've rotated the motor/compressor so it wouldn't be binding.

If you think you'll be too slow, put your leads on the place you'll be measuring voltage, and have somebody flip the switch for you.

If the motor itself is humming I would be looking at the capacitors or the motor itself.

 

[4rcFed]

I received my new pressure switch with an on/off lever today and installed it. No change, as expected.

Also, I checked the capacitors, which have a rating of 710-850mF.
The left one tested at 744mF.
The right one tested at 739mF.

I checked the incoming voltage across the top two lugs on the motor starter, which read 225VAC when the breaker was turned on.

Those are the readings so far.

 

[930dreamer]

Have you tried running the motor with the belt off? Is that a reset button in the starter pics?

 

[4rcFed]

I have not tried with the belts off, but can do that easily.

There is an overload relay on the bottom. I have not checked any voltages across those terminals.

 

[930dreamer]

I have not tried with the belts off, but can do that easily.

There is an overload relay on the bottom. I have not checked any voltages across those terminals.

I was wondering if it needs to be reset? i.e. pushed in?

 

[mtnkrake]

The diagram that you have posted shows the pressure switch hooked between the No3 terminal and the No1 terminal. Have you tried it that way?

 

[retrobuilder]

Piping- Sharpe (spray equipment) has great piping diagram, i had a compressor similar to yours and had to run a slow blow breaker..

 

[4rcFed]

Have you tried running the motor with the belt off? Is that a reset button in the starter pics?

I checked the voltage between the red wire at the bottom of the overload relay across the black wire at the bottom of the motor starter, which checks out at 222VAC.

But, I did run out to take the belts off. I spun everything again by hand (belts on) and everything spins freely. But, with the belts off, it sounds like an old washing machine coming up to speed (slowly), but the motor was turning. But it only spins for a few seconds before tripping the breaker.

So I think I found something.

 

[4rcFed]

The diagram that you have posted shows the pressure switch hooked between the No3 terminal and the No1 terminal. Have you tried it that way?

The diagram that someone else posted pn the first page of this thread shows the switch hooked up between the No1 and No3 terminal, which is the way I think it is hooked up.

By looking at the white and black wires in the close-up pic on page two, I think they are that way. I need to go confirm, but I think it is.


But the main point is that something happened at once. Everything was working fine, nothing changed, the next day - no worky.

 

[retrobuilder]

Does the motor bearings have oil ports? Maybe dry..I imagine you'd done that one though.

 

[4rcFed]

Does the motor bearings have oil ports? Maybe dry..I imagine you'd done that one though.

Nope, did not do anything to that sort.

 

[retrobuilder]

"Fred", can you hook up an ammeter/ multi-meter and measure the amp draw and line voltage at start? If so compare amps to motor rating. Is it something as simple and $$$ as the motor bad$. If it has oil ports apply a few drops of air tool oil into the ports (at end of motor shaft if it has them). Then hand spin several turns. then retry motor. Best of luck.

 

[4rcFed]

Well, I'll have to wait till tomorrow to try to check the amp draw. My wife, the breaker flipper, went to bed for the night.

But I checked the label of the motor and it made no mention of oiling directions. But there are plugs at both ends of the motor case leading to the shaft. I pulled the rear plug, looked inside, and it has plenty of grease in there. Still need to check the front though.

Checking the amp draw, would I put the multimeter on the red lead at the bottom of the overload relay and the black lead at the bottom of the motor starter? Is that where you'd check that?

(sorry, electrically challenged!!)

 

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[wyliesdiesels]

Well, I'll have to wait till tomorrow to try to check the amp draw. My wife, the breaker flipper, went to bed for the night.

But I checked the label of the motor and it made no mention of oiling directions. But there are plugs at both ends of the motor case leading to the shaft. I pulled the rear plug, looked inside, and it has plenty of grease in there. Still need to check the front though.

Checking the amp draw, would I put the multimeter on the red lead at the bottom of the overload relay and the black lead at the bottom of the motor starter? Is that where you'd check that?

(sorry, electrically challenged!!)

Nope. Your gonna need a clamp meter as most multimeters do very limited amp reading(upto about 10a) and u have to put the meter in series with the circuit, on an unfused terminal. So its pissible to burn out the meter. U can get a basic clamp meter at home depot for $60! A clamp meter has a circular disc at the top, which opens in half at the push of a lever to enable the user to put the clamp around wires. And you only measure one motor lead at a time!

 

[KenC]

It's beginning to sound like a start winding or start switch problem. If you motor has a centrifugal start switch it may be stuck or dirty and not engaging the start windings. If it has a timed start circuit the starter timer may be bad.

 

[dbonne]

I checked the voltage between the red wire at the bottom of the overload relay across the black wire at the bottom of the motor starter, which checks out at 222VAC.

But, I did run out to take the belts off. I spun everything again by hand (belts on) and everything spins freely. But, with the belts off, it sounds like an old washing machine coming up to speed (slowly), but the motor was turning. But it only spins for a few seconds before tripping the breaker.

So I think I found something.

From what I am reading in all of the posts, especially your last post your motor has a bad start switch. On single phase capacitor start, capacitor run motors that need large starting torque, there is a centrifugal switch that connects when the motor is stopped or lower than a preset speed. If the switch doesn't connect, the motor will attempt to start like you are saying slow and without power, tripping the breaker. If the switch doesn't disconnect when it reaches speed, it will start fast, making a loud humming noise then trip the breaker. There could be a couple of problems, one being the contacts are burned and pitted from thousands of operations, for which you can clean the points (will only work for a while) or you can get a replacement switch from your local motor shop or on the internet for 20 to 30 dollars. Secondly, the motor centrifugal mechanism may be broken (broken spring) or just bound up, not letting the points come back together at zero speed.

In order to get to the switch, you will have to remove the motor and pull the closed end bell from the motor. Be careful, the switch is usually bolted to the end bell, be observant of taking it apart in order to not break anything else as you are pulling it apart. Label all of your wires clearly!!!! If you have any questions, look up your motor model on internet and find an electromechanical breakdown.

Here is a generic diagram of the CSCR (split phase) motor:

View media item 30246
Hope you find this helpful!

 

[dbonne]

KenC, You beat me to the punch! Good Call!!

 

[4rcFed]

Alright KenC and dbonne......I'm going at this from your expertise!!!

Butif I read your stuff right, then I should take the motor off of the compressor, remove the electrical panel from the side, and then remove the long through bolts shown in the picture below??




Label of motor:

 

[wyliesdiesels]

I checked the voltage between the red wire at the bottom of the overload relay across the black wire at the bottom of the motor starter, which checks out at 222VAC.

But, I did run out to take the belts off. I spun everything again by hand (belts on) and everything spins freely. But, with the belts off, it sounds like an old washing machine coming up to speed (slowly), but the motor was turning. But it only spins for a few seconds before tripping the breaker.

So I think I found something.

I dont know why i didnt catch this earlier! Your voltage is pretty low, actually too low because when that motor starts the voltage will drop even further and thus the motor will draw more juice! The voltage should be closer to 240v +/- 5%! Can u test the voltage at your main service panel? What is the size of the breaker feeding the compressor?

 

[4rcFed]

I'll check that value again, but I thought that seemed low for just being on the other side of the motor starter.

I'll re-check that and also check the panel voltage and report back.


Thanks guys for all of the troubleshooting assistance!!

 

[dbonne]

You can probably do all of the work with the motor on the tank, providing it is not too high to comfortably work on it. Here is a simple procedure:

1. Remove (lockout) all power to the unit!!
2. Disconnect the negative wire on the battery. (sorry, couldn't resist)
3. Remove Belts (takes the tension off the bearings in the end bell), leave the pulley on the motor and leave motor bolted to frame.
4. Mark the closed end bell and the motor casing, draw a line across the seam between the end bell and the motor casing to aid in reassembly
5. Remove 4 through bolts on motor, I cannot see if there are nuts on the open end, probably not.
6. Using a dead blow hammer tap the end bell while pulling on it, this should open up a gap big enough to pull it with a couple of pry bars. Be mindful that the start switch is attached to the end bell, If you look into the vents in the bottom of the motor with a flashlight you will see the switch inside.
7. The bearing will stay on the rotor, however there is a spring washer that might fall out, don't worry, it is the diameter of the bearing and is easy to get back in place.
8. If the end bell came off, you should be looking at a switch on the end bell attached by a couple of wires, mark the wires!!! take a couple of pictures
!! You should be able to tell that the contact points are burned. If they are clean, push on the plate on the rotor centrifugal switch, it should click back when you release it.

Google the part number on the switch, you should find one easily.

You might be able to clean the points and reassemble, In my travels, this is only a temporary at best fix.

Reassemble in the opposite manner, the end bell should go on fairly easy, the spring washer keeps the bearing from spinning in the housing.

Let me know how or if this is your problem!! Good Luck!!

Bones

 

[dbonne]

Also, from the looks of the nameplate, your motor is rated for a full load startup at 208 volts.

 

[4rcFed]

Well, I did a bit more checking today. Long story short, I tested the voltage at the bottom of the motor starter and still got about 223VAC, so I checked the top.....and I once checked and thought it was good, but today was at 223VAC.

I then checked the outgoing side of the 30A Eaton circuit breaker, only to find 223VAC.

I pulled the cover off of the panel, and checked the incoming wires and got 242VAC. I pulled the breaker and checked the hot bus bars and got around 241VAC.

Put the breaker back in, and still got 223VAC on the outgoing side. I happened to have another brand new breaker (same 30A Eaton type) and still got 223VAC on the outgoing side.

I just checked the outgoing side of the breaker above it, which goes to the welder outlet and it measured 241VAC.

WTH?

 

[wyliesdiesels]

That is very wierd that it happened with 2 new breakers! Try the breaker in another spot on the bus bars i guess. Or another 'NEW' breaker maybe!

 

[G_P]

Corrosion on the bus bars in the panel?

Shut down the main breaker and use a scotchbrite pad to clean em up and reinstall the breaker and test voltage again.

Or try putting the breaker in a different place in the panel. If the low voltage follows the breaker then get a new breaker.

Sent from my C5120 using Tapatalk 2

 

[4rcFed]

That is very wierd that it happened with 2 new breakers! Try the breaker in another spot on the bus bars i guess. Or another 'NEW' breaker maybe!

Tried a couple things today.

Measured the buss bars in various locations, all ~242VAC.
Measured the outgoing lugs on the double pole breaker above the air compressor location, measured ~242VAC.

Remeasured the outgoing side of the Eaton 30A breaker for the compressor, still measured ~223VAC. (I have to switch it on but the compressor motor hums and the breaker eventually trips).

I swapped out the location for the compressor breaker and my welder breaker. But once swapped, it still measured ~223VAC.

Went to the store and tried a different brand breaker (GE), installed it, still measuring 223VAC. It is an old Crouse Hinds panel and wasn't sure if there were brand specific breakers that needed to be in there. Looks like the previous home owner has an array of different breakers installed.

So I did a test each with the GE and Eaton breakers installed, but not hooking up the wires to the compressor. Then I measured the outgoing lugs of the breaker. They measured ~242VAC.

So what would cause the drop in voltage, measured at the breaker, once the wires of the compressor are inserted into the circuit breaker???

 

[Kevin C]

Could be some kind problem getting an accurate measurement. A very high resistance with no load will read close to line voltage, but once you put a load on it it should drop to close to zero volts.

EDIT

Try running a drop light from each leg to neutral to see if it works.... Double check your DMM readings with the load of the drop light on each leg.

 

[4rcFed]

Just stumped now.....not sure if the problem resides in the power supply (electrical panel) or if it is within the compressor.

****.

 

[Kevin C]

With a helper:

Put your meter across the mains of the panel.

Have your helper try and start the compressor.

If the voltage stays up.... Your feed is OK and the problem is down stream.

If it drops.... More on that later.

Try the same thing a bit down stream. A quick flip of the load , just long enough to get a reading.

At some point you can also try at the motor itself.

 

[KenC]

Tried a couple things today.


Remeasured the outgoing side of the Eaton 30A breaker for the compressor, still measured ~223VAC. (I have to switch it on but the compressor motor hums and the breaker eventually trips).

emphasis above mine. I think you're seeing voltage drop due to the motor loading the circuit. I think you need to measure the voltage without the motor trying to run and I'll bet you see the correct level.

Have you worked on the centrifugal switch yet???

 

[wyliesdiesels]

Wylie, short circuit conditions and ground faults are considered overcurrent conditions, and the breaker would trip on instantaneous, but these small molded case breakers typically trip on instantaneous at around 10X the breaker rating.



The overloads are sized according to the motor horsepower, and is the motors primary protection. The breaker is sized to protect the wire.

Ok, so explain to me how a fuse or breaker feeding a motor circuit protects the wire when its sized at 175%(fuses) or 300%(breakers) of motor FLC but the wire is sized at 125% of motor FLC. This is the reason why i said earlier that the overloads protect the wire and motor and the breaker(or fuses) protect against short circuits and ground faults. The link i referenced to a thread on Mike Holts site also conveys the same thing!

(Not trying to be a smart ***, just trying to understand where you're coming from because i was always taught and understood this a different way!)

Just stumped now.....not sure if the problem resides in the power supply (electrical panel) or if it is within the compressor.

****.

OP- have u tried testing the caps as suggested earlier in the thread? (Sorry if u already posted this as this thread is pretty long now!)

 

[4rcFed]

Yep...getting long!

Caps checked out ok.

Next move when I get a minute is to pull the motor apart for a look. But tomorrow is Mother's Day....so I may not get to it tomorrow.

 

[4rcFed]

Ok...got a chance to pull the motor down. Besides normal dust and dirt, I did see some mud-dobber work in there.

But...what so I need to check from here?

 

[dbonne]

It looks as if your centrifugal mechanism is ok, you should be able to push the washer on the shaft towards the rotor and it will click in and back out. Next I would inspect the switch contacts on the back side of the orange start switch plate. Make sure they aren't burned and pitted real bad. The contact points can be lightly sanded with fine sand paper, but if burned should be replaced. Best way to check the switch is to hook 2 wires to the switch, run them out the vent hole in the motor, put the end bell on the motor. Put an ohmmeter on the 2 wires and you should get anywhere from .1 ohm to 5 ohms. The switch should basically be a short circuit across the terminals while the motor is stopped.

 

[4rcFed]

The pictures came out bad, but it doesn't "look" bad inside.

But I did what you said to try. The motor is still off of the compressor, but I hooked the leads up, put the end bell back on, and got a fluctuating reading of 0.1 and 0.2 Ohms.

 

[dbonne]

Dude, Sounds like start switch is out of the equation. Clean that motor up inside and put it back together. By chance did you check the motor leads to ground with an ohmmeter? T1 and T2 should have very high resistance to ground (like in the Megohm range).

 

[4rcFed]

I didn't do that, but I tried tonight. What is the proper way to do that?

I found two wires, one labeled T1 and the other T4 (picture in post 38 on page 2), so I believe those are the motor leads. They are each clumped in a grouping of three wires. One motor lead wire, one wire going to the overload relay/motor starter, and the other to a capacitor.

I took off the wire nut, took the wires apart, and then took my multimeter and hooked the motor lead up to one terminal and then the other to a ground, but I don't get a reading. I'm doing something wrong here.

 

[dbonne]

Not getting a reading is a good thing, you do not want any continuity to ground.

 

[4rcFed]

That's what I thought when I was all said and done, but wanted to make sure that I was doing things correctly.

I just didn't know at what point should I run this down to a shop to have it tested, but there really isn't one too close to just stop by, so I wanted to investigate as much as possible.

But now I'm stuck! What else can I check?